In general, an epoxy compound are produced by subjecting an olefin compound to oxidation reaction in the presence of an organic peroxide such as peracetic acid or performic acid, but in this production method, there are problems such that the organic peroxide is corrosive, the oxidation reaction tends to be out of control, and an addition product of the organic peroxide as a byproduct remains in the resulting epoxy compound.
Therefore, a method for oxidizing an olefin compound with hydrogen peroxide in place of the organic peroxide has been studied. This production method is advantageous industrially because hydrogen peroxide as an oxidizing agent is not corrosive, the oxidation reaction is under control, and the byproduct is only water.
However, it is difficult to oxidize olefins with hydrogen peroxide only. Thus, for example, in JP-A-2004-115455, JP-A-2003-192679, Bull. Chem. Soc. Jpn., 70, 905-915 (1997), and J. Org. Chem., 61, 8310 (1996), a method of subjecting an olefin compound to oxidation reaction effectively in an organic solvent containing an aqueous hydrogen peroxide solution and a combination of a quaternary salt compound and a heteropoly acid is disclosed. However, a large amount of the quaternary salt compounds remain in the epoxy compound obtained by this production method.
Therefore, for example, a method where a chemically activated carbon is added to an organic solution containing an epoxy compound and a quaternary salt compound so that the quaternary salt compound is physically adsorbed on the activated carbon is disclosed in JP-A-2010-70480. However, since the activated carbon also adsorbs other substances in addition to the quaternary salt compound, its amount used is increased and this is not economical.
Meanwhile, the quaternary salt compound is also considered to be removed by various chemical adsorption means. Such means include, for example, use of an aqueous cyclodextrin solution as described in JP-A-2008-246287 and use of an ion exchange resin as described in JP-A-2007-181833.
However, both means are intended to remove a quaternary salt compound contained in an aqueous solution and are not suitable for removal of a quaternary salt compound contained in an organic solution. For example, when the aqueous cyclodextrin solution is added to an organic solvent solution containing an epoxy compound and a quaternary salt compound, an emulsion occurs, therefor it becomes difficult or impossible to remove the quaternary salt compound. Further, since an ion exchange resin is typically hydrophilic and difficult to be wet with an organic solution, it is actually difficult to adsorb the quaternary salt compound contained therein on such a resin.